1. Field of the Invention
This invention relates to a subminiature lamp used as a signal or indicator for home appliances, audio-visual products and office equipment, or the like, and more particularly to a composition of a subminiature lamp that is used with a socket disposed on a printed wiring board by soldering, or the like.
2. Discussion of the Related Art
FIGS. 5 and 6 illustrate conventional subminiature lamps used as a signal or indicator. The subminiature lamp 90 in FIG. 5 is to be mounted from the back surface of a printed wiring board 20. This subminiature lamp 90 assembly has a bulb 91, a socket 92, and a pair of lead wires 91a penetrating through the socket 92. The socket 92 includes a bulb holder 93 which is formed as a cylinder with a bottom to maintain the bulb 91 within the cylinder, and also includes a socket base 94 to mount the subminiature lamp 90 on the printed wiring board 20.
The bulb 91 of the conventional lamp 90 in FIG. 5 is mounted in the bulb holder 93 in the socket 92 by pulling out the pair of lead wires 91a through holes in the bottom of the bulb holder 93 to the back surface of socket base 94. Each of the pair of lead wires 91a is wound around each end 95 of the socket base 94. Since the bulb 91 is installed by penetrating through the printed wiring board 20, the back surface of the printed wiring board 20 faces the front surface of the socket base 94. Accordingly, the front surface of the socket base 94 must be designed to satisfy this mounting requirement.
The subminiature lamp 80 in FIG. 6 is installed on the front surface of the printed wiring board 20. This subminiature lamp 80 assembly has a bulb 91, a socket 82, and a pair of lead wires 91a passing through the socket 82. The socket 82 includes a bulb holder 83 which is formed as a cylinder with a bottom to maintain the bulb 91 within the cylinder, and the socket base 84 to mount the subminiature lamp 80 on the printed wiring board 20. In this composition, since the subminiature lamp 80 is installed on the front surface of the printed wiring board 20, and therefore does not pass through the printed wiring board, the socket base 84 touches the front surface of the printed wiring board 20.
The conventional subminiature lamps 90 and 80 have at least the following two problems. First, the compositions of the subminiature lamps 90 and 80 are difficult to produce when mounted on the printed wiring board 20, because the lead wires 91a are very fine and must go through the socket bases 94 and 84 by passing through holes existing in the bottom portion of the bulb holders 93 and 83. Second, since there are differences with respect to how to mount the subminiature lamp 90 and 80 on the printed wiring board 20, even though the basic properties of the lamps are the same, two kinds of the subminiature lamps 90 and 80 are required depending on the mounting conditions designated by customers. This may often change the production plan and consequently lower productivity.